Fellow Kiwi here. Sorry is the first thing I would say, and dang that it has extended this long, I get you'd be feeling a bit down and like when the heck is this going to come to an end.
CHFather is right, oxygen - it's key. Were you able to get the GP to write a letter and refer you to your DHB respiratory team for funded supply? If not - push back on the GP hard. They probably don't know the protocol. If respiratory team denied cover, push back again - ask for a reason in writing from your GP and to see the correspondence (and send it to me so I have it on record along with my own tribulations - I am not going to let this rest, we need change in NZ re access to o2 as it is inconsistent and I believe comes down to lack of education). If you can't get it funded and can afford to pay for it, then it would be worth it - all you need is a letter from your GP (if they won't write it up, tell them to get on the phone to the on-call neurologist and seek their advice, that's what they are supposed to do). Send letter to BOC's medical team and they will setup an account and you can go get oxygen or have delivered. You need the Cluster o2 kit for breathing apparatus.
Vitamin D3 regimen. Your doctor can prescribe D3 capsules without testing and they are subsidised, ask for 12x 50,000iu - most GP's will just write it up. You can get the lab test you need by going to lab tests and paying for it. You can get most of the other supplies at at pharmacy less the D3 and K2 (order from iHerb - 7 days its here). It's worth asking your doctor to write up the lab for calcium and PTH and most won't know how to interpret the test so just tell them to make sure it's uploaded to your portal - the D3 regimen quick start guide explains how to navigate this. I can't offer medical advice clearly but you can ask me for my opinion by sending me a message with the lab values and any other questions. Starship gives kids the same amount 5-18yrs 600,000iu as a one time dose, no testing (Stoss protocol) so make what you will of that - I suggest be practical and sensible with supplementing D3 but it's nowhere near as dangerous as some would suggest.
Busting - do you have supplies and is it an option for you. I needed to do this during my recent cycle, if you need to discuss, DM me.
Verapamil, what dose did they start you on and what formulation, extended or immediate release? How many times a day are you taking it?
Did you consider a pred taper to see if that would, cross fingers, disrupt the cycle enough to abort it?
Try dropping carbs - I am not saying go carnivore, just as the D3 regimen guide calls for anytime you fall from remission or the D3 base regimen doesn't get you pain free, go keto but include whole foods. Consider adding some of the full monty supplements on top of the standard D3 stack being curcumin, resveratrol, melatonin, quercetin.
I realize I have thrown shit at you hoping something might stick, please forgive if you have tried any of these and/or any of what I said has been taken the wrong way.
If you just want support - message me. I am sorry again, hopefully you are able to find the tools and support to get out of this cycle. Hang in there.